Stemfie, The 3D-Printable Construction Set

August 13, 2024 by Lewin Day 3 Comments

Construction kit toys are cited by many adults as sparking great creativity and engineering talent in their youth. LEGO, Meccano, K’NEX, Lincoln Logs—these are all great commercial options. But what about printing your very own construction kit at home? Meet Stemfie.

Fundamentally, Stemfie isn’t that different from any other construction kit you might have seen before. It has various beams and flat plates that are full of holes so they can be assembled together in various ways. It also uses bolts, spacers, and small plastic nuts that can be tightened using a special hand tool. Think of a mixture between LEGO Technic and Meccano and that will get you in the ballpark. It includes neat motion components too, including gears, wheels, and even a large flat spring!

What can you build with it? Well, as every construction kit toy says, you’re only limited by your imagination! However, if your imagination is especially small, you can just use the Stemfie 3D YouTube channel for inspiration. It features everything from a ping pong ball catapult to a rubber-band driven car. Plus, since it’s all 3D printed, you can simply scale up the parts and build even bigger designs. Like a giant catapult that can hurl entire water jugs. Fun!

We’ve seen other projects in this vein before. One of our favorites is [Ivan Miranda]’s giant 3D printed assembly kit that he uses to build big monster toys.

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RC Submarine Build Starts With Plenty Of Research

August 13, 2024 by Orlando Hoilett 19 Comments

[Ben]’s a 15-year-old who loves engineering and loves taking on new challenges. He’s made some cool stuff over the years, but the high water mark (no pun intended) has to be this impressively documented remote controlled submarine.

His new build starts off with more research than the actual building. [Ben] spent a ton of time investigating the design of the submarine from its shape, to the propeller system, to the best way to waterproof everything, keeping his sub in tip-top shape. He decides to go with the Russian-style Akula submarine, which is probably the generic look that most of us would think of when we hear the word submarine. He had some interesting thoughts on the propeller system (like the syringe ballast we’ve seen before), and which type of motor to use. In the end, he decided with four pumps that would act essentially as thrusters. ~~fill a chamber with water, allowing the submarine to submerge, or fill with air, making the submarine buoyant, allowing it to resurface.~~

However, what we found most interesting about his build is how he explains the rationale for all his design decisions and clearly documents his thought process on his project page. We really can’t do [Ben]’s project justice in a short post, so head over to his project page to see it for yourself.

While you’re at it, check out some of these other cool submarine builds that we’ve featured here on Hackaday

A painted RC plane made of cardboard. It has an orange propeller and camo-esque markings along with concentric blue, white, and red circles near the wingtips.

Cardboard R/C Plane Actually Flies

August 1, 2024 by Navarre Bartz 19 Comments

Many makers start by building mock-ups from cardboard, but [Alex-08] has managed to build an R/C plane that actually flies, out of cardboard.

If you’ve been thinking of building an R/C plane from scratch yourself, this guide is an excellent place to start. [Alex-08] goes through excruciating detail on how he designed and constructed this marvel. The section on building the wings is particularly detailed since that’s the most crucial element in making sure this plane can get airborne.

Some off-the-shelf R/C parts and 3D printed components round out the parts list to complement the large cardboard box used for most of the structural components. The build instructions even go through some tips on getting that vintage aircraft feel and how to adjust everything for a smooth flight.

Need a wind tunnel instead? You can build that out of cardboard too. If paper airplanes are more your thing, how about launching them from space? And if you’re just trying to get a head start on Halloween, why not laser cut an airplane costume from cardboard?

OSHW Model Rocket Kit Embraces The Hexagon

July 27, 2024 by Tom Nardi 20 Comments

If you’ve ever built a model rocket, you’ll know there’s not a whole lot to them. Essentially it’s a cardboard tube, a plastic nosecone, some fins, and a little clip that will keep it riding the launch rail as it accelerates off the pad. Extra points awarded if you add in a parachute, but strictly speaking, even that’s a luxury. Stick an Estes motor in that thing and send it.

But pointing out that lightweight cardboard tubes can be tricky to ship without getting crushed, [Concrete Dog] has come up with HEXA, a clever model rocket kit that uses pre-scored cardstock instead. The immediate advantage is that this allows the rocket to be shipped as flat sheets of material, but as a secondary bonus, once folded into its final shape the rocket has an awesome hexagonal cross section.

As with a traditional kit, both the nosecone and fins are plastic. Except here they’ve been 3D printed in either PLA or PETG depending on their proximity to he hot and fiery area of the rocket. [Concrete Dog] says the printed parts are largely ready to fly as-is, but that some quality time with a piece of sandpaper and a coat of paint could improve the aerodynamics a bit if you were so inclined.

Ready for the best part? [Concrete Dog] has decided to release all of the design files for the rocket under the CERN Open Hardware Licence, meaning you’re free to reproduce and modify the rocket as you see fit. In fact, on July 24th, the HEXA rocket was officially certified as Open Hardware by the Open Source Hardware Association (OSHWA) — a first for a DIY rocket, as far as we can tell.

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A custom LEGO throne for Dune's Baron Harkonnen.

A Throne For LEGO Baron Harkonnen

July 22, 2024 by Kristina Panos 2 Comments

If you’re both a LEGO and a Dune fan, unless you’ve been living in a cave on Mars with your eyes shut and fingers in your ears, you’re probably aware that LEGO released a set for the royal Atreides ornithopter. The blades flap and everything. Anyway, it comes with several minifigures, including one that doesn’t quite fit with the others — a full-length Baron Harkonnen.

Given that, [gorkyver] decided to create a throne for the Baron that he could rise from, just like in the movie, while delivering the iconic line. With no reference materials available other than pausing the movie, [gorkyver] created a throne from scratch in BrickLink Studio, which made it easy to generate both a parts list and step-by-step instructions.

At the heart of this build is an Arduino Nano, which takes input from the momentary push button and starts the show. The Baron slowly rises on a rack and spur gear connected to a stepper motor, and a DF Player Mini runs the audio through a 75 mm speaker.

Rather than just buying a big box store display case off of eBay, [gorkyver] recreated the skeleton in Fusion 360 and used a hairdryer to bend a sheet of PET-G around to enclose it. A couple of sweet adhesive graphics later, and it totally looks like a real set on display. Don’t miss the demo/build video after the break.

Did you hear? The European Space Agency printed some bricks out of meteorite dust, and there might be one on display near you.

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Sealed Packs Of Pokémon Cards Give Up Their Secrets Without Opening Them

July 20, 2024 by Donald Papp 31 Comments

[Ahron Wayne] succeeded in something he’s been trying to accomplish for some time: figuring out what’s inside a sealed Pokémon card packet without opening it. There’s a catch, however. It took buying an X-ray CT scanner off eBay, refurbishing and calibrating it, then putting a load of work into testing and scanning techniques. Then finally combining the data with machine learning in order to make useful decisions. It’s a load of work but [Ahron] succeeded by developing some genuinely novel techniques.

While using an X-ray machine to peek inside a sealed package seems conceptually straightforward, there are in fact all kinds of challenges in actually pulling it off. There’s loads of noise. So much that the resulting images give a human eyeball very little to work with. Luckily, there are also some things that make the job a little easier.

For example, it’s not actually necessary to image an entire card in order to positively identify it. Teasing out the individual features such as a fist, a tentacle, or a symbol are all useful to eliminate possibilities. Interestingly, as a side effect the system can easily spot counterfeit cards; the scans show up completely different.

When we first covered [Ahron]’s fascinating journey of bringing CT scanners back to life, he was able to scan cards but made it clear he wasn’t able to scan sealed packages. We’re delighted that he ultimately succeeded, and also documented the process. Check it out in the video below.

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You Can Build A Little Car That Goes Farther Than You Push It

July 11, 2024 by Lewin Day 25 Comments

Can you build a car that travels farther than you push it? [Tom Stanton] shows us that you can, using a capacitor and some nifty design tricks.

[Tom]’s video shows us the construction of a small 3D printed trike with a curious drivetrain. There’s a simple generator on board, which charges a capacitor when the trike is pushed along the ground. When the trike is let go, however, this generator instead acts as a motor, using energy stored in the capacitor to drive the trike further.

When put to the test by [Tom], both a freewheeling car and the capacitor car are pushed up to a set speed. But the capacitor car goes farther. The trick is simple – the capacitor car can go further because it has more energy. But how?

It’s all because more work is being done to push the capacitor car up to speed. It stores energy in the capacitor while it’s being accelerated by the human pushing it. In contrast, after being pushed, the freewheeling car merely coasts to a stop as it loses kinetic energy. However, the capacitor car has similar kinetic energy plus the energy stored in its capacitor, which it can use to run its motor.

It’s a neat exploration of some basic physics, and useful learning if you’ve ever wondered about the prospects of perpetual motion machines.

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